Allergic dermatitis: symptoms, diagnosis, treatment

By Cristiano Antonino On Apr 17, 2023

Allergic dermatitis is an inflammatory disease affecting the skin. It is also known as allergic eczema and is not contagious

In infants and children, allergic eczema is often the result of a reaction due to a food allergy.

Allergic dermatitis: what is it?

Allergic dermatitis is an inflammation of the skin that is caused by the body’s reaction to certain substances, called allergens, whether chemical or natural.

These elements are perceived as dangerous by the body, which triggers an immune response, causing more or less severe skin irritation.

The most common symptoms are erythema, swelling, itching or the formation of small blisters and vesicles.

The severity depends on the individual patient and the areas that come into contact with the substance.

Often, however, the irritation affects the whole body.

Allergic dermatitis can be treated using topical remedies, such as cortisone-based creams, to reduce swelling, itching and inflammation.

In any case, it is recommended to avoid contact with the allergen altogether. A patch test by a dermatologist will be necessary to identify the substance responsible for the disease.

Causes of allergic dermatitis

Allergic dermatitis is caused by contact with substances, called allergens, that provoke an overreaction of the immune system.

After the first contact between the allergen and the skin has occurred, the immune cells become sensitised.

This means that they will recognise the substance much faster in the future.

Allergic dermatitis is immediately manifested by itching, swelling and reddening of the skin.

After the first exposure, the patient usually shows symptoms after a few weeks, while on second contact, when the body is already sensitised, the disease manifests itself much more rapidly.

In more sensitive individuals, allergic dermatitis may also occur in areas that are far away from the area of contact.

Symptoms of allergic eczema

The symptoms of allergic dermatitis are quite obvious and include erythema, inflammation, constant itching, irritation, swelling, dysepithelialisation and scabs, accompanied by vesicles.

The lesions are most often confined to the area of contact, but may also spread to other areas.

After the first contact with the allergen, as already mentioned, allergic dermatitis may occur after a few days.

The first symptom is an inflammation of the affected area, followed by itching and redness.

The condition progresses with the appearance of blisters and vesicles that burst, creating unsightly lesions and scabs that are painful and annoying.

Over time, allergic dermatitis can become chronic and degenerate, leading to changes in the skin that becomes thick and tough, covered in scales with marked pigmentation.

Allergic dermatitis: Diagnosis

The diagnosis of allergic dermatitis is made with a patch test.

This test involves placing potentially allergenic substances in contact with the skin for a period of 48 hours.

The application takes place with the use of white discs, held in place by patches, that cover the skin.

Two readings can be taken after two days to assess whether or not allergic dermatitis has developed.

If the area shows itching, blisters, swelling and erythema, the test is positive.

This means that the patient is allergic to that substance.

The reading of the test is rather complex, which is why it can only be performed by a specialist.

Allergic dermatitis: allergens that trigger it

There are many allergens that can trigger allergic dermatitis.

From perfumes to synthetic substances that are present in many products, such as medicines or cosmetics.

For most people, these substances are harmless, but when they come into contact with sensitive individuals, they can cause a lot of damage.

In fact, the body, upon intercepting a potential danger, activates an immune response, triggering the allergic manifestation.

Even a small amount of allergen is sufficient to cause allergic dermatitis.

Unlike intolerance, the dose the body is subjected to is not important, but the other symptoms of food allergies, such as nausea, diarrhoea or vomiting, are not present.

Among the most common allergens are metals such as nickel and cobalt.

In particular, these substances frequently cause harm because they are found in many everyday objects.

Nickel is found in costume jewellery, accessories, glasses and scissors. Cobalt can be found in dyes and paints, paper, cosmetics in shampoo, nail polish and disinfectants.

Another metal linked to allergic dermatitis is chromium, which is present in large quantities in cement.

Allergens can also be of plant origin, such as propolis, essential oils and Peruvian balsam.

These are elements that can be found in detergents and cosmetics and can trigger the condition.

Dermatitis, the areas of the body most affected

Certain stroke areas are more prone to suffer from allergic dermatitis.

Most often, this pathology affects the face, a very sensitive and exposed area due to the use of cosmetics and beauty products that may contain allergens.

If the patient is sensitive to certain metals, such as nickel, allergic dermatitis may occur on the ears, wrists and neck due to the use of jewellery or perfumes.

In some individuals, the disease occurs in the armpits, due to the composition of deodorants, or on the hands.

This last part of the body is often the one where the allergic reaction occurs most frequently because it is the one that comes into contact with the most objects.

How is allergic dermatitis treated?

Allergic dermatitis has no specific treatment. The only way to treat the disease is to prevent it.

After the first allergic reaction, which leads to sensitisation, the patient should avoid contact with the substance that triggers the disease.

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This condition becomes problematic when it is impossible to avoid contact with the allergen.

In this case, topical medicines such as corticosteroids, which provide a powerful anti-inflammatory action by modulating the immune response, can be used.

In particular cases, the doctor may decide to prescribe the patient an oral corticosteroid treatment.

Natural remedies, on the other hand, are considered ineffective.

Allergic nickel dermatitis

Nickel is an element found in various metals. It can be found in jewellery as well as in everyday objects such as keys, spectacle frames, zips or coins.

As it is found in soil, a certain concentration of nickel can also be found in foods, such as dried fruit, cocoa, whole grains, seafood and many vegetables.

Since it is impossible to determine precisely how much of the substance is present in foods, individuals with nickel allergic dermatitis are given a diet that involves successive elimination of different foods.

This allows exposure to be reduced and the sources of the allergic reaction to be identified.

Numerous studies have shown that the percentage of people allergic to this substance, which remains the most common cause of allergic dermatitis, is increasing.

This is referred to as systemic nickel disease.

The onset can occur within 24 to 36 hours after first contact with symptoms such as inflammation, skin dryness, itching, blisters and small lesions.

The latter should be treated immediately using steroid creams or antihistamine tablets according to the doctor’s instructions.

The rash usually resolves itself by avoiding contact with the allergen.

Allergic chromium dermatitis

Chromium allergic dermatitis is considered less common than nickel allergic dermatitis.

Nevertheless, it should by no means be underestimated.

Chromium is in fact a substance that is widely used in industrial processing.

It can be found in leather goods, leather clothing and many fabrics as it is used to fix colours.

This metal is also a component of cement, which is why it is widely used in construction, and it can be found in paints and bleaches.

Chromium is also a substance used in cosmetics: it is the basis for colouring hair dyes and nail polishes.

Finally, just like nickel, chromium can be found in many foods, such as eggs, veal, turkey, beef, wholemeal flour, beer, mushrooms, potatoes and cocoa.

Among those most exposed are those who work in construction, but also those who have tattoos.

Chromium is often found in yellow-green tattoo pigments.

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